Cadillac Catera/Opel Omega owner contemplating V8 swap

[The Tobacconist]

Hi

I recently purchased a 2000 Cadillac Catera and was quite impressed by the nice build quality, handling and overall refinement. What I don’t like about the car however is the anemic and gutless little 200 hp 3.0L V6 that resides under the hood, it just doesn’t cut it. One thing I was also very suspired by was the poor gas mileage especially on the highway compared to my 1996 Impala SS with a 300 hp 5.7L LT1. The Impala actually gets noticeably better mileage! After checking EPA statistics I was quite surprised by that fact that the Catera’s mileage is no different than comparable 3L 200hp V6 vehicles such as the Honda Accord and Toyota Camry. Yet another incentive for a V8 swap.

I’m considering an LS6 or LS2 which is dimensionally identical to the Australian LS1 that came in the Commodore. I know that there will be many issues involved with this swap but right now I have 2 questions:

1) From my understanding the Australian chassis was 2 inches wider to accommodate the V8. Though this will make the swap more difficult it will not be impossible as I have seen several Catera V8 swaps in magazine and Opel was considering a production V8 and had multiple prototypes.

I’m getting conflicting information though on how exactly was the Australian chassis different; were only the strut towers mover 2 inches apart while the cars overall width was the same as the German built Catera and Omega, or was the whole car widened? Also could anyone post close-up pics of strut tower to header clearance on the Australian cars?

2) The Omega and Catera came with a much weaker rear differential. I was considering just getting one from the new GTO, but from my understanding it is mounted completely differently from the Catera and Australian 4-door Commodore. So do the Commodore and Monaro really use different differentials with the Commodore part being interchangeable with the Catera? Also would anyone have any pics of the Commodore rear end as well as GM part numbers and cost in Australian dollars?


Thanks!

[cheffy]

youll find that the diff is identical between the commodore and the monaro. You could quite easily fit it in I would think if you were to make a custom set of extractors. We just put one into a VR commodore which wasn't very difficult and that has a narrower engine bay than the Vt/vx which the ls1 came out in.

[Sid447]

The Commodore/Monaro/GTO

Is virtually identical underneath. Yes the diff is different, but the whole of the rear suspension, when eye-balled looks the same.
Maybe the cradle that the diff bolts to has some differences.
The front suspension is different in asmuch as the Opel/Cadillac uses a lower A arm which looks almost like a wishbone (much better than the TCA and separate radius rod set-up of the GM-H car).

Front Track for the VT/VX model sedans are: 1569mm
Rear Track: 1587mm.
Wheelbase: 2789mm.
Overall Width: 1842mm (excluding mirrors)
Overall Length: 4964mm.

If you send me your email by PM I'll pass on some of the info I have from the Holden Service manual.

[German Statesman]

Hmmm....digging into the deep recesses of my memory for this one - I was working for a Holden dealer at the time of the launch of the VT and there were later comparisons to the Omega/Catera.

From what I remember, the VT is a 'pumped out' version of the Catera/Omega platform, and not only is it wider, but the wheelbase is longer too from memory. We also had wagon and ute versions which were unique to Oz too.

The diff in the Commodores was straight out of the Opel handbook, but strengthened for our big torque motors. My advice is to adapt a 9 inch Ford diff to your Catera halfshafts - pretty common here with the race cars.

Good luck

[The Tobacconist]

The Commodore/Monaro/GTO

Is virtually identical underneath. Yes the diff is different, but the whole of the rear suspension, when eye-balled looks the same.

I was told that the differential mounting design was revised when GM changed the fuel tank location so they could bring the Monaro (Pontiac GTO) to the US. Do the Australian Monaro's also use the US trunk mounted fuel tank?

Front Track for the VT/VX model sedans are: 1569mm
Rear Track: 1587mm.
Wheelbase: 2789mm.
Overall Width: 1842mm (excluding mirrors)
Overall Length: 4964mm.

I found this.



I'm not too familiar with those names, is the VT the Commodore and the VX the even larger Australian full size Caprice/Statesman?

[The Tobacconist]

So could anyone give me a part # for the Holden differential, I'm wondering a GM dealer here in Canada could order it for me.

[Dacious]

The two letter code signifies the model year. So VT is 1996-2000, VX from 2000-2002, VY from late 2002-2004, VZ from late 2004 - 2006. VE will be a 2007 model intro'd in Sept. 2006. The new model year starts in the Australian spring. From VT-VZ, the greenhouse or centre bit is the same - the guards, bonnet (hood), boot (trunk) and detail item changes.

Tobacconist, I doubt you can order Holden parts via GM US. Some GTO guys tried this - even when they have the part no. the system there does not recognise it. Holden here uses a different parts inventory system.

However, just order the GTO diff. It is 3.46:1 and the exact same unit as the SIII VY/VZ Monaro or 2004/2005 GTO. Even though Oz is part of the same NAFTA as Canada and the US, Canadian duties on the diff and more importantly freight from Oz will cancel any price advantage ordering direct from Holden. You could even get a unit from a wrecked GTO of which there are a few.

Beware that you will also have to use the ECU (2-of?) from the GTO to drive the LSx EFI as it is completely different to the electrics on the Catera. The LS2 uses a completely different unit to the LS1/LS6, not only for FBW throttle but also other parameters in the motor.

Series I-III Monaros 2001-2004 used a tank in the base of the trunk, which the spare sits in. VZ Monaros (late 2004-on) have the same setup as the GTO - it was standardised to make it easier on the line. Obviously the boot (trunk) goes from being a little tight (SIII) to stupidly small in VZ.

Also beware - the Catera is not engineered for the power of a big V8. The Holden's gross vehicle weight in some versions is roughly double the Omega, and although parts like suspension members might look the same, cross sections, bushing and bearings etc. are likely a lot different. It is fair to say the Holden is likely a lot stiffer and stronger in the body.

The Holden not only has a longer wheelbase/wider track, but the wheels are also pushed out to the corners of the car for handling/stability, too. You'd also run out of stock Opel brakes pretty quick. It might be easier to adapt the new HFV6 out of the Cadillac CTS - it is what we get, 3.6, VVT and 254 hp. Good unit.

[Jac001]

I'm not too familiar with those names, is the VT the Commodore and the VX the even larger Australian full size Caprice/Statesman?

the statesmane/ caprice models are based on the wagon verson of the respective VT/VX etc model but made into a long wheel base sedan.

[The Tobacconist]

The two letter code signifies the model year. So VT is 1996-2000, VX from 2000-2002, VY from late 2002-2004, VZ from late 2004 - 2006. VE will be a 2007 model intro'd in Sept. 2006. The new model year starts in the Australian spring. From VT-VZ, the greenhouse or centre bit is the same - the guards, bonnet (hood), boot (trunk) and detail item changes.

So are the VT, VX, VY and VZ all the same chassis with merely cosmetic revisions which is essentially the 1994 GM corporate V-platform? Or were there any significant changes such as wheelbase or track?

However, just order the GTO diff. It is 3.46:1 and the exact same unit as the SIII VY/VZ Monaro or 2004/2005 GTO. Even though Oz is part of the same NAFTA as Canada and the US, Canadian duties on the diff and more importantly freight from Oz will cancel any price advantage ordering direct from Holden. You could even get a unit from a wrecked GTO of which there are a few.

It appears that the GTO and Catera differentials are indeed mounted differently.

GTO

http://www.ee-performance.com/Diff%2...20Side%201.jpg

http://www.bmrfabrication.com/gto/Co...risonLarge.jpg

Catera

http://img58.imageshack.us/my.php?im...teraend5eq.jpg

But apparently earlier Commodores used the same mounting scheme as the Catera. If only I could find a picture on the Commodore rear end to confirm this.

Beware that you will also have to use the ECU (2-of?) from the GTO to drive the LSx EFI as it is completely different to the electrics on the Catera. The LS2 uses a completely different unit to the LS1/LS6, not only for FBW throttle but also other parameters in the motor.

Yup, the electronics are not interchanagble at all. I planned on getting the correct PCM for the motor I decide to go with.

BTW do any of the Australian cars come equipped with the FBW like the Corvettes?

The Holden not only has a longer wheelbase/wider track, but the wheels are also pushed out to the corners of the car for handling/stability, too. You'd also run out of stock Opel brakes pretty quick. It might be easier to adapt the new HFV6 out of the Cadillac CTS - it is what we get, 3.6, VVT and 254 hp. Good unit.

Merely 50hp would simply not make such an undertaking worth it. Also V6’s just sound like crap.

I also plan to upgrade to the Cadillac CTS-V 4 piston Brembo's (same brakes that the new Viper SRT-10 has). I get a cost discount from my dealer so I pay bit over $300 USD for both front calipers with pads

[Dacious]

So are the VT, VX, VY and VZ all the same chassis with merely cosmetic revisions which is essentially the 1994 GM corporate V-platform? Or were there any significant changes such as wheelbase or track?

BTW do any of the Australian cars come equipped with the FBW like the Corvettes?

Merely 50hp would simply not make such an undertaking worth it. Also V6’s just sound like crap.

I

All HSV VZ V8s with LS2, plus (I think) Monaro have the FBW - not sure about the SS and S.

Essentially all Commodores apart from the LWB Utes, Wagons and Luxo-barges from VT-on have the same wheelbase - I think track might have varied slightly. 2001 VX Series II Holdens, all VX HSV and all Monaros got the toe-control link which Opel used all along to prevent uneven rear tyre wear and bad handling.

Other than that, they get different ride height, spring/dampers, steering racks and wheel/tyre combos to separate them. AWD models have wider track to fit in driveshafts and extra diffs.

Yep, the chassis stamping, and passenger cell are very much the same from '96-now, although with VY in '02 they moved the B-pillar slightly to improve side crash protection IIRC. To produce the LWB cars, they cut the chassis stamping in front of the rear wheels, and weld in a fillet which adds 7-8" of length. Saves having two sets of $200m body dies.

[Sid447]

".....BTW do any of the Australian cars come equipped with the FBW like the Corvettes?....

All models of Monaro and Commodore V8 had cable activated T/Body to end of MY2004 I believe. Someone like "Dacious" should be able to verify this.

[Fighter]

Hi , it is possible to swap the engine . In 2001 opel germany build the omega with an cheverolet V8 , and make promotion , but they never sell this modell because there were some problems with the cooling of the head of the engine .
one month in front of the coming out opel make a cut . so everybody who order this omega v8 had bad luck :-(

and the cadilac catera is the same like the opel omga

greetings

Heiko

[Stormin]

Even though Oz is part of the same NAFTA as Canada and the US, Canadian duties on the diff and more importantly freight from Oz will cancel any price advantage ordering direct from Holden.

Australia is not party to NAFTA, only Canada, Mexico and USA.